Sharp Kabushiki Kaisha Corporation

Hiroshi Tatsumi

Atsushi Inoue

Takayuki Yamanaka

Takashi Sakai

Tadashi Iwamatsu

Tetsuro Toyoshima

Toshihiko Takaya

Hiroshi Ishii

Nobuyuki Azuma

Masanori Yamada

Kazuhiro Matsuyama

Eiichi Kido

Keiji Yasuda

Katsumi Adachi

Masahiro Sakai

Toshihide Ohgoshi

Jitsuo Masuda

Yukihito Nishio

Shigeyuki Wakada

Nobuhiko Nakano

Chiaki Yamawaki

Mikie Kobayashi

Blade for a developing device

A developing apparatus designed to allow toner uniformly charged with a predetermined electric charge to be formed into a toner layer formed on a circumferential surface of a developing roller, and further to allow a good image to remain formed. In order to allow a proper amount of toner having a proper specific electric charge to deposit on the circumferential surface of the developing roller, the blade is bent at a bending angle of at least 45&deg; while being positioned against the circumferential surface of the developing roller when displacement amount &Dgr;L is at most plus 0.4 mm.

Developing apparatus

A cleaning element is arranged on the backside of the toner layer metering blade, i.e., the side opposite to the surface in contact with the developer support, in order to prevent the cleaning element from damaging the blade surface and the abutment surface of the metering blade against the developer support. This cleaning element is frictionally moved across the backside of the toner layer metering blade to remove stuck toner from the toner layer metering blade or prevent occurrence of buildups.

Developer unit with cleaning element

In a mono component toner developing device, a developing roller supporting and conveying the mono component toner is arranged in contact with a photoreceptor supporting a static latent image. A supplying roller is arranged opposing the developing roller with a predetermined contact depth. The supplying roller has a pair of driven gears fixed at both ends of the rotational shaft thereof for being rotated so as to be meshed with a pair of driving gears rotated by a driving motor. The rotational force of the driving gears, acting at a coupling position, is used to deflect the supplying roller toward the developing roller side, whereby the supplying roller is pressed in approximately uniform contact with the developing roller across its full length along the shaft.

Toner developing device for an image forming apparatus

A developing unit having an elastic blade which is provided with rectangular holes along the width in the area between its abutment portion against a developing roller and the supported end.

Developing unit having elastic blade

A developing apparatus includes: a first rotary member; a second rotary member having an elastic surface and adapted to be rotated in contact with the first rotary member. A contact depth controlling roller is kept in rotative free engagement with each end of a shaft of the second rotary member and having an outer circumferential surface abutting against the first rotary member and an inner circumferential surface abutting against the shaft of the second rotary member for keeping a contact depth of the second rotary member abutting against the first rotary member at a predetermined level. A controller is provided so as to rotate the second rotary. This structure, for example, eliminates the need for bearings.

Contact depth controlling roller mechanism

An image forming apparatus has a photoreceptor drum and a developing roller supported in the developing unit for retaining and conveying the developer, and further has a sealed viscous fluid damper having a viscous fluid sealed therein, arranged coaxially with the rotary shaft of the photoreceptor drum.

Image forming apparatus

A blade is pressed against a developing roller for regulating the amount of toner which is deposited on a surface of the developing roller. The blade is formed with a slant face at its tip end, to which the toner is transported along a direction of rotation of the developing roller. An angle of aperture .theta. at a toner inlet portion defined by the developing roller and the slant face is set at 12.5.degree. or more, the angle of aperture counting in an angle .psi. of the slant face, elastic deformation and radius (R) of the developing roller, and an angle .alpha. related to a nip width w on which the blade contacts with the developing roller. Such an angle of aperture .theta. provides a great allowance for a free length l of the blade, thereby permitting the blade to maintain a constant toner mass for forming a uniform toner layer.

Developing apparatus using one-component toner

A developing apparatus includes a toner carrier for transferring toner to a development position, a layer-thickness regulating member for forming a toner layer having a predetermined thickness on the toner carrier by making contact in a leading edge or a surface of a vicinity of the leading edge with the toner carrier, and a supplier for supplying a one-component toner to the toner carrier. Also combined with the layer-thickness layer is a vibration absorbing device allowing the toner to be applied in a uniform thickness. The vibration absorbing device can also be a sealing member located on the toner carrier. Each sealing member can be two different materials effective to absorb vibration.

Developing apparatus with vibration absorbtion device

The object of the invention is to certainly remove and certainly recover the charged toner remaining on a developing roller after development. A single component toner which is delivered to the developing roller via a toner-supplying roller is made into a relatively thin layer of a predetermined thickness with a charging plate and is frictionally charged with a given quantity of electric charge. Subsequently, the toner is adhered on a photoreceptor drum along by the electrostatic latent image to develop an image at the developing region at which the developing roller comes into contact with the photoreceptor drum. After development, the electric charge of the toner layer on the developing roller is removed with an electric-charge-removing sheet. The toner after development is recovered into a toner hopper via the toner-supplying roller. In rotation direction of the developing roller, the relation of the width Wt of the toner layer to the width Wc of the electric-charge-removing sheet is established so as to be Wc.gtoreq.Wt. Thus, the electric charge of the toner layer on the developing roller is certainly removed.

Developing apparatus having means for removing electric charge of toner

A switching element and a protective resistance are connected between a developing roller and a developing bias source. A switching element switches on and off a connection between the developing roller and the developing bias source. A protective resistance is connected to the switching element in series. There is a controller and a bias stabilizer. The controller switches on the switching element when a developing bias voltage is to be applied to the developing roller and switches off the switching element when the developing roller is caused to be in an electrically floating state without applying the developing bias voltage, and which bias stabilizer is disposed between the developing roller and a ground and maintains a predetermined stable voltage only when the switching element is switched on. The structure enables a high-quality image to be formed with a low power consumption.

Monocomponent development apparatus

To prevent scattering of toner when an image forming operation is started and ended in a developing process using one-component toner, a rotatable developing roller in contact with a photosensitive member carrying a static latent image, which is used to carry and feed one-component toner, is provided in a developing tank containing one-component toner. Initially, toner is fed to a feed roller, then passed through a toner restricting member which is pressed against the developing roller to restrict the amount of toner to be fed, so that a layer of toner is formed at a fixed thickness and fed into a developing area in contact with the photosensitive member. Thus a static latent image is produced on the developing roller. In this process, a developing bias voltage Va is supplied to the developing roller, a restricting voltage Vb is supplied to the toner restricting member so as to fix the thickness of the toner layer, and a supply voltage Vc is supplied to the feed roller to control the supply of toner. Specifically, the developing bias voltage Va, restricting voltage Vb, and supply voltage Vc are applied to their respective objects before the developing roller begins rotating, thereby minimizing or preventing the scattering or blowing out of toner. Additionally, supply of those voltages Va, Vo, and Vc are stopped after the developing roller stops, which also helps to prevent excess scattering of toner.

An elastic member for pressing is provided in a prescribed location in an area where the developer carrier comes in contact with the discharging member, in order to bring the discharging member into contact with the developer carrier so that mechanical peeling of the residual developer on the developer carrier is not caused, and the discharging member is provided with a bias power supply for setting bias in a direction imparting to the discharging member a force for electrically drawing the residual developer on the developer carrier away from the developer carrier, and after thus reducing the electric adhesion of the residual developer to the developer carrier, the developer feed member removes the residual developer on the developer carrier in the vicinity of disjunction area or in the contact area of the developer carrier and the developer feed member, thereafter applies new developer in a developer container to the developer carrier in the vicinity of approaching area or in the contact-starting area of the developer carrier and the developer feed member.

Image developing device using a one-component toner

A differential amplifier amplifies a PG reproduction signal to a level permitting signal processing. A low-pass filter makes the signal waveform of a PG detection signal generated by the differential amplifier substantially uniform irrespectively of the rotational speed of a rotating drum. A comparator outputs a PG pulse by comparing an output of the low-pass filter with a threshold. A magnetic recording and reproducing apparatus having such a structure can detect the PG pulse with accuracy over a rotational speed range requiring a precision control of the rotating drum.

Phase detecting circuit of brushless motor and magnetic recording and

A brushless motor driving device includes a comparator. The comparator compares a control voltage with a control signal in proportion to a control current of each Hall element. An output of the comparator is amplified by a Hall element driving amplifier, and is inputted to a control current terminal of each Hall element as an error signal. Each Hall element outputs a Hall signal based on an inputted error signal. The driving voltage is controlled such that an amplified Hall signal matches with a driving voltage applied to each driving coil. The brushless motor driving device permits a brushless motor to be stably driven at any rotation speed from low-speed rotations till high-speed rotations with a simple circuit structure.

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Shiki-gun, Japan

Hiroshi Tatsumi